Implantable electrical stimulation systems have proven therapeutic in a variety of diseases and disorders. For example, stimulation systems may be employed in the spinal cord to treat chronic pain syndromes and in the brain to treat refractory chronic pain syndromes, movement disorders, and epilepsy. Similarly, stimulation systems employed peripherally may prove beneficial for the treatment of chronic pain syndrome and incontinence. In some instances, functionality may return to paralyzed extremities in spinal cord injury patients by electrical stimulation. Moreover, electrical stimulation systems may be implanted subcutaneously to stimulate subcutaneous tissue including subcutaneous nerves such as the occipital nerve, and the trigeminal nerve.
Though these stimulation systems vary in design, they include the same core elements—a control module (with a pulse generator), one or more leads, and an array of stimulator electrodes on each lead. The stimulator electrodes are placed in contact with or near the nerves, muscles, or other tissue to be stimulated. The pulse generator in the control module generates electrical pulses that are delivered through the lead and the electrodes to body tissue.
Target areas may include the face (facial nerves such as the trigeminal nerves), the skull, or limbs. For peripheral and subcutaneous target areas in thin patients, standard diameter leads may not be suitable. Similarly, for deep brain stimulation, where a cannula is passed through a tract in the brain, smaller leads may be more beneficial as they displace less brain tissue, minimizing potential irreparable damage.